1. Field of the Invention
The present invention relates to an apparatus for producing trichlorosilane and a method for producing trichlorosilane through conversion of silicon tetrachloride to trichlorosilane.
Priority is claimed on Japanese Patent Application No. 2010-032999, filed Feb. 17, 2010, the content of which is incorporated herein by reference.
2. Description of Related Art
Trichlorosilane (SiHCl3) is used as a raw material for producing silicon (Si). The trichlorosilane can be produced by conversion of silicon tetrachloride (SiCl4) through a reaction of silicon tetrachloride and hydrogen.
Silicon is produced by the reductive reaction and the thermolysis reaction of trichlorosilane shown by the below-described reaction formulae (1) and (2), and trichlorosilane is produced by the conversion reaction shown by the below-described reaction formula (3).SiHCl3+H2→Si+3HCl  (1)4SiHCl3→Si+3SiCl4+2H2  (2)SiCl4+H2→SiHCl3+HCl  (3)
For example, as an apparatus for producing trichlorosilane, Japanese Patent No. 3781439 proposes a reaction vessel having a reaction chamber of dual structure constituted of an outer chamber and an inner chamber formed by two tubes of concentric alignment, and a heating element disposed to surround an outer circumference of the reaction chamber. In this reaction vessel, the heating element is formed of carbon or the like and constitutes a heating section (heater), and the reaction of a gas in the reaction chamber is caused by heating the reaction chamber from outside by the heat generated in the heating element through energizing of the heating element.
An apparatus disclosed in Japanese Unexamined Patent Application, First Publication No. 2004-262753 has a structure in which a reaction chamber is constituted of an inner tube and outer tube in a concentric alignment, and a heating element (heater) is disposed to surround the reaction chamber.
In an apparatus for producing trichlorosilane proposed in Japanese Unexamined Patent Application, First Publication No. 2008-133170, a reaction chamber is constituted of a plurality of cylindrical walls in a concentric alignment, and circular plates that close the upper side and lower side of spaces formed between the walls, where each of the spaces are communicated continuously, and a heating element is disposed in inner side of the innermost cylindrical wall.
Japanese Examined Patent Application, Second Publication No. S60-49021 discloses an apparatus in which a plurality of pipe-shaped heaters are disposed inside the reaction chamber, and a gas is directly heated in the reaction chamber and within the heaters.
Where an apparatus has a structure as described in Japanese Patent No. 3781439 or in Japanese Unexamined Patent Application, First Publication No. 2004-262753, interior of the reaction chamber is heated by the heating element disposed outside the reaction chamber. In this case, heat from the heating element is radiated not only in the inner radial direction but also in the outer radial direction, resulting in a disadvantage of low heat efficiency.
On the other hand, where an apparatus has a structure as described in Japanese Unexamined Patent Application, First Publication No. 2008-133170, it is possible to heat the gas with higher heat efficiency than that of the apparatus of Japanese Patent No. 3781439 since the heating element is disposed to the central position of the reaction vessel, making it possible to transfer the entire heat radiated in the outer radial direction to the gas. However, since a reaction chamber is formed to surround the outer circumference of the heating element, an increase of the outer diameter of the reaction chamber results in an increase of distance between the heating element and a circumferential portion of a space in the reaction chamber. Therefore, there is a limitation for increasing the size of the apparatus in order to increase the production.
Where an apparatus has a structure as described in Japanese Examined Patent Application, Second Publication No. S60-49021, it is possible to utilize the heat of the heater with high efficiency since the heater is disposed inside the reaction chamber. However, the entire gas is not heated uniformly unless the gas flows uniformly in the reaction chamber and flows in each of the heaters uniformly. Therefore, there is a possibility of reduction of reaction efficiency due to heterogeneous heating of the gas.
Based on the consideration of the above-described problems, an object of the present invention is to provide an apparatus for producing trichlorosilane and a method for producing trichlorosilane that enables heating of supply gas with improved high heat efficiency, that enables increasing the size of the apparatus without reducing the heat efficiency, and that enables mass production of trichlorosilane.